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Optical Multistage Interconnection Networks: New Challenges and Approaches
 IEEE Communications Magazine
, 1999
"... Optical interconnections for communication networks and multiprocessor systems have been studied extensively. A basic element of optical switching networks is a directional coupler with two inputs and two outputs (hereafter referred to simply as switching elements or SEs). Depending on the control v ..."
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Cited by 16 (7 self)
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Optical interconnections for communication networks and multiprocessor systems have been studied extensively. A basic element of optical switching networks is a directional coupler with two inputs and two outputs (hereafter referred to simply as switching elements or SEs). Depending on the control voltage applied to it, an input optical signal is coupled to either of the two outputs, setting the SE to either the straight or the cross state. A class of topologies that can be used to construct optical networks is multistage interconnection networks (MINs), which interconnect their inputs and outputs via several stages of SEs. Although optical MINs hold great promises and have demonstrated advantages over their electronic counterparts, they also introduce new challenges such as how to deal with the unique problem of avoiding crosstalk in the SEs. In this paper, we survey the research carried out, including major challenges encountered and approaches taken, during the past few years on opt...
Permutation capability of optical multistage interconnection network
 JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING” , PP.60,
, 2000
"... In this paper, we study optical multistage interconnection networks (MINs). Advances in electrooptic technologies have made optical communication a promising networking choice to meet the increasing demands for high channel bandwidth and low communication latency of highperformance computing/commu ..."
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Cited by 12 (6 self)
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In this paper, we study optical multistage interconnection networks (MINs). Advances in electrooptic technologies have made optical communication a promising networking choice to meet the increasing demands for high channel bandwidth and low communication latency of highperformance computing/communication applications. Although optical MINs hold great promise and have demonstrated advantages over their electronic counterpart, they also hold their own challenges. Due to the unique properties of optics, crosstalk in optical switches should be avoided to make them work properly. Most of the research work described in the literature are for electronic MINs, and hence, crosstalk is not considered. In this paper, we introduce a new concept, semipermutation, to analyze the permutation capability of optical MINs under the constraint of avoiding crosstalk, and apply it to two examples of optical MINs, banyan network and Benes network. For the blocking banyan network, we show that not all semipermutationsare realizable in one pass, and give the number of realizable semipermutations. For the rearrangeable Benes network, we show that any semipermutation is realizable in one pass and any permutation is realizable in two passes under the constraint of avoiding crosstalk. A routing algorithmfor realizing a semipermutationin a Benes network is also presented. Withthe speed and bandwidthprovided by current optical technology, an optical MIN clearly demonstrates a superior overall performance over its electronic MIN counterpart.
Equivalent Permutation Capabilities Between TimeDivision Optical Omega Networks and NonOptical ExtraStage Omega Networks
 IEEE/ACM Transactions on Networking
, 2001
"... Because signals carried by two waveguides entering a common switch element would generate crosstalk, a regular multistage interconnection network (MIN) cannot be directly used as an optical switch between inputs and outputs in an optical network. A simple solution is to use a 2 2 cubetype MIN to p ..."
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Cited by 9 (2 self)
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Because signals carried by two waveguides entering a common switch element would generate crosstalk, a regular multistage interconnection network (MIN) cannot be directly used as an optical switch between inputs and outputs in an optical network. A simple solution is to use a 2 2 cubetype MIN to provide the connections, which needs a much larger hardware cost. A recent research proposed another solution, called the timedomain approach, that divides the optical inputs into several groups such that crosstalkfree connections can be provided by an regular MIN in several time slots, one for each group. Researchers studied this approach on Omega networks and defined the class set to be the set ofpermutations realizable in two time slots on an Omega network. They proved that the size of is larger than the size of class\Omega , where\Omega consists of allpermutations admissible to a regular (nonoptical) Omega network. This paper first presents an optimal ( log ) time algorithm for identifying whether a given permutation belongs to class or not. Using this algorithm, this paper then proves an interesting result that the class is identical to the class\Omega 1which represents the set of permutations admissible to a nonoptical oneextra stage Omega network. Index TermsConflict graph, crosstalkfree connection, dilated MIN, Omega network, optical switch, timedomain approach. I.
A TwoLevel Process for Diagnosing Crosstalk in Photonic Dilated Benes Networks
 JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING
, 1997
"... A twolevel process for diagnosing crosstalk in photonic Dilated Benes Networks (DBNs) is presented. At level one is the TestAllSwitches (TAS) procedure, which obtains the crosstalk ratios of each and every switch in a N x N DBN in 4N tests using O(N \Delta log² N) calculations. One of its applica ..."
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Cited by 3 (0 self)
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A twolevel process for diagnosing crosstalk in photonic Dilated Benes Networks (DBNs) is presented. At level one is the TestAllSwitches (TAS) procedure, which obtains the crosstalk ratios of each and every switch in a N x N DBN in 4N tests using O(N \Delta log² N) calculations. One of its applications is to identify single or multiple crosstalkfaulty switches in the DBN which generate excessive crosstalk. To reduce the number of tests and amount of computation when diagnosing only a few switches suspected of crosstalkfaulty along an arbitrary path, the TestOnePath (TOP) procedure at level two is proposed. A recursive algorithm applicable to both procedures is used to configure the DBN for each test such that the necessary power measurements of the signals can be taken accurately. An important feature of the proposed diagnostic process is its suitability for automated test generation.
Analyzing the performance of optical multistage interconnection networks with limited crosstalk
, 2007
"... Analytical modeling techniques can be used to study the performance of optical multistage interconnection network (OMIN) effectively. MINs have assumed importance in recent times, because of their costeffectiveness. An N × N MIN consists of a mapping from N processors to N memories, with log 2 N ..."
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Cited by 2 (0 self)
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Analytical modeling techniques can be used to study the performance of optical multistage interconnection network (OMIN) effectively. MINs have assumed importance in recent times, because of their costeffectiveness. An N × N MIN consists of a mapping from N processors to N memories, with log 2 N stages of 2 × 2 switches with N/2 switches per stage. The interest is on the study of the performance of unbuffered optical multistage interconnection network using the banyan network. The uniform reference model approach is assumed for the purpose of analysis. In this paper the analytical modeling approach is applied to an N × N OMIN with limited crosstalk (conflicts between messages) up to (log 2 N − 1). Messages with switch conflicts satisfying the constraint of (log 2 N − 1) are allowed to pass in the same group, but in case of a link conflict, the message is routed in a different group. The analysis is performed by calculating the bandwidth and throughput of the network operating under a load l and allowing random traffic and using a greedy routing strategy. A number of equations are derived using the theory of probability and the performance curves are plotted. The results obtained show that the
A Novel Multistage Network Architecture with Multicast and Broadcast Capability
"... Abstract. In this paper, a new class of optical multistage interconnection network (MIN) architecture is presented, which is constructed utilizing a modularization approach rather than the traditional recursive or fixed exchange pattern methods. The modified architecture consists of an input module, ..."
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Cited by 1 (0 self)
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Abstract. In this paper, a new class of optical multistage interconnection network (MIN) architecture is presented, which is constructed utilizing a modularization approach rather than the traditional recursive or fixed exchange pattern methods. The modified architecture consists of an input module, an output module, two pointtopoint (PTP) modules, and one modified multicast/broadcast (M/B) module(s). We also implement the multicast/broadcast module with WDM technique, which reduces the hardware cost required for multicast and the recomputation cost for a new connection. We show that it has the best application flexibility and provides multicast function without imposing significant negative impacts on the whole network. A new multicast connection pattern is also proposed in this paper, which makes it practical and economical to apply amplification in spacedivision networks. Compared with existing multicast architectures, this new architecture with Dilated Benes PTP modules has better performance in terms of system SNR, the number of switch elements, and system attenuation in pointtopoint connections. Moreover, the multicast/broadcast module adopts wavelength division multiplexing (WDM) technique to increase its multicast/broadcast assignment. As a result, given m available distinguished wavelengths, one M/B module can support at most m M/B requests at the same time. The new proposed M/B module with WDM is more practical and economical to apply amplification in spacedivision networks.
Analysis of SpaceTime Tradeoffs in Photonic Switching Networks
 Proc. of Infocom 96
, 1996
"... A photonic switching network may be dilated in either space or time to establish crosstalkfree connections. Spacetime tradeoffs are evaluated using an analytical model based on Markov process. The probability that a new connection can be established without crosstalk is calculated by taking into c ..."
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A photonic switching network may be dilated in either space or time to establish crosstalkfree connections. Spacetime tradeoffs are evaluated using an analytical model based on Markov process. The probability that a new connection can be established without crosstalk is calculated by taking into consideration the traffic correlations between stages. The model is applicable to both Banyan and dilated Banyan networks under either switch or stage control. Our results imply that spacetime tradeoffs are improved by using Banyans instead of dilated Banyans. If hardware cost is not a concern, a multiplane Banyan network, which is more effective than a dilated Banyan, may be used. 1 Introduction Optoelectronic conversions required by electronic switching can become an impediment in high bitrate (e.g. above 50 Gbs) optical communication systems [3]. Photonic switching networks are useful since they can provide virtually unlimited communication bandwidth, as well as bitrate and coding f...